Cold gun issues

Discussion in 'Long Range Hunting & Shooting' started by GPR23, Nov 6, 2018.

  1. GPR23

    GPR23 Active Member

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    I have ran into an odd situation. I have done a lot of testing in the past two weeks trying to figure out the cause. I have gotten it better but still has an issue.

    To start with I had acquired a Ruger M77 MKII 22-250. I replaced the barrel with a Mcgowen in Sendero profile, lightened the trigger, and put it in a Hogue full aluminum bed stock. I did the standard load testing and came up with a very accurate load shooting 53gr v-max. I thought I would try making it more accurate and bedded the action, but really didn’t result in any improvements and cause some headaches.

    The problem I have is when the gun is warm, such as a 70-80 degree day (when I did load development) the gun will shoot great. However, if the gun is cold the first shot is always low out of the group. Then the next few will settle down and shoot in the normal group.

    To test what the cause of the large spread I have done several test first thing in the morning. I would leave either the gun and ammo, just the ammo or just the gun outside so it would be cold. I would fire 3-5 rounds and see how they performed. The ammo grouped the same whether cold or hot, but if the gun was cold it always shoots the first shot low. When the gun is warm I don’t see the issues.

    I have included a picture of this morning’s test. I also labeled the shots. Normally they aren’t vertically strung out this perfect.

    What would cause this? I was almost to the point of ordering another stock, but there really aren’t many options for Ruger stocks with a heavy profile barrel.

    Any ideas or suggestions on where to go? When warm, this gun is one of the most accurate guns I have. However, i built it as a coyote gun and i have no confidence in the first shot.
     

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  2. GPR23

    GPR23 Active Member

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    Here is a group, when i first started to notice something off. The first group is the bottom left. Second group is bottom right. Third group is top right (and yes that is a 3 shot group I wouldn't have believed it myself, but i was shooting a target on a bucket and the backside you could clearly see 3 bullets exit), then the last group is top left. It isn't as great as i was in a time crunch and rushed them.
     

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  3. GPR23

    GPR23 Active Member

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    Here are a few cold test groups. Its a little confusing the order so here is the explanations.

    Middle left is cold gun, cold ammo test. I then put it into the original wood stock and left it cold and shot the middle right group, basically same issue.

    I decided reinstall it into the hogue stock but this time I remove the bedding epoxy. Shot the top left group with the action in the Hogue stock with no bedding now. It is better, but the gun was also warm.

    Top right is with no bedding, cold gun and cold ammo.

    Bottom left group is a warm gun and warm bullets. Probably about a 3/4" moa.

    then the wind blew away the target and i put up a new one which was shot this morning. It is in the first post and is a cold gun with warm ammo. Seems anytime the gun is cold it shoots bad. I think with out the action bedded it is better, but not great.
     
  4. FIGJAM

    FIGJAM Well-Known Member LRH Team Member

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    Is the barrel making any contact with the stock? I am guessing that normally the hogue stock free floats the barrel...maybe the bedding did something funky and is causing some contact somewhere?
     
  5. GPR23

    GPR23 Active Member

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    The barrel is free floated.
     
  6. FIGJAM

    FIGJAM Well-Known Member LRH Team Member

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    Sorry man - I am at a loss...I'll be following this thread out of curiosity.
     
  7. Hand Skills

    Hand Skills Well-Known Member

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    What have you tried for torque on the action screws?
     
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  8. GPR23

    GPR23 Active Member

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    The front tang screw I always torque to 90in lbs as i believe that is what ruger recommends. the other two i have done differently. This last time after removing the bedding i put them hand tight.
     
  9. bullfrog

    bullfrog Well-Known Member

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    I would try it in the factory stock just to see if it behaves the same. On my rugers bedded onto aluminum block stocks (HS precision and Hogue) I torque the front and rear screws to 60 in/lbs and the center screw just barely tight enough to hold the trigger guard securely. If you look at the boyds stocks website there are a lot of options for Rugers in laminate stocks.
     
  10. GPR23

    GPR23 Active Member

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    I tried it in the factory wood stock, and it didn't help any. However it is a wood stock and i had to open it up so much the for-end had to be weekend.

    The issue i have is it is a Sendero contour barrel. I have asked Boyds, and they don't recommend opening up their stocks for a Varmint profile barrel.....

    I was planning on trying different torque spec for tomorrow mornings test. I thought Ruger recommend 90in lbs on the front screw? maybe i need to look around or ask Hogue what they recommend.
     
  11. Hand Skills

    Hand Skills Well-Known Member

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    Wouldn't hurt to try 45in/lbs and 60in/lbs to see.

    Before you start pulling your hair out (if you're not past that point already), try giving the scope a couple of firm taps with the back of a screwdriver before you shoot. I've lost a few hairs chasing a similar problem - turned out it was related to the scope.

    Now whenever something goes funny, the first thing I do is mount a known working optic.

    Good luck in your quest!
     
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  12. 26Reload

    26Reload Well-Known Member

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    How could this be a stock problem unless the shooter is torquing it before the shot...if OP is shooting off of sandbags or sticks or bipod...we need to know....
    Obviously pressure on the barrel or the stock before shooting will/should inadvertently cause poi problems....
    But a severe jump like this seems to be torque...whether it be on the stock, the barrel or the scope bases or rings....but only on a cold shot.....theres obviously a link we are missing.....what about clean barrel vs dirty barrel shooting........clean that hell out of it and start again....from scratch...
    Pull everything(stock, scope, rings and bases) apart and rebuild it...
    See what happens....
    I know a couple I have had in past shot really good dirty.....at least i never made the effort to clean perfectly....brush guns...most the time just glad they shot......
    Good luck...
     
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  13. The Oregonian

    The Oregonian Well-Known Member

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    I will get lower velocity on a cold bore shot...I would put a chrono on it and my guess is it is lower velocity - and if so, just run a dope for that velocity...i would add 1/4 MOA at 500 to get ideal vertical alignment at the range. For hunting I am not really worried about it unless I want to get precise at 500 and beyond...then I add the 1/4 MOA.
     
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  14. Classic12

    Classic12 Well-Known Member

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    Still trying to wrap my head around what could be the culprit following the thread..